Recovery of useful product from spent doctor



Patented Oct. 13, 1953 T UNITED STATES PATENT OFFICE RECOVERY OF USEFUL PRODUCT FROM SPENT DOCTOR John B. Holtzclaw, Roselle, and John D. Brooks, Elizabeth, N. J., assignors to Standard Oil Development Company, a corporation of Delaware Application July 23, 1952, Serial No. 300,538 2 Claims. (01. 252-183) The present invention is concerned with a procpolysulfides. The spent doctor solution withess for segregating valuable products from a spent drawn from the heating oil treatment contains process for the treatment of a doctor solution 5 solution is passed to a settling zone wherein the winch has been used in the t1 eatment of mercapsame is contacted with hydrogen sulfide tan containing naphthas and heating oils In ac- T e process of the pi esent invention may be tion with hydrogen sulfide, followed by the sepa- I by means of line 2. Caustic is introduced into ration of the segregated layer and treatment of r zone I by means of line 3 and withdrawn as the segregated layer with a caustic solution, folspent caustic by means of line 4. The treated oil plumbite solution converts the mercaptans to drawn by means of line 8. A treated oil is withsulfur to form disulfides and lead sulfide. ther handled or refined as desired. It is to be The doctor or plumbite solution is prepared by understood that zones i and 6 may comprise any I dissolving lead oxide in sodium hydroxide as suitable number and arrangement of stages.

follows: A heating oil fraction boiling in the range from (Sodium Plumbite) about 430 F. to 750 F. is introduced into caustic PbO ZNaOH S N ZP l H10 treating zone In by means of line I I. Fresh Upon treatment of the mercaptan containing oil Caustic is introduced o Z 0 0 by means of normal lead mercaptide and basic lead mercapof line I3. treated oil is removed from zone III Na2PbO2+ 2RSH (RS) 2Pb+2NaOH NazPbOz-I- RSH+H2O RSPbOH 2N aOH solution th drawn f Upon the addition of sulfur the relatively ininto the treating zone by means of line 29. A nocuous disulfides are formed and lead sulfide is heating oil product is removed from zone I5 precipitated as follows: 2y I1eaI1Sd0f linie I Iand furtthgr handleidtor rene as esire e spen 00 or so u ion is (RS) fggk withdrawn from zone I5 by means of line I] and g' gggi 40 passed into a settling zone I8. The solution segregates into a top oil layer containing dis- In these reactions the spent doctor solution is solved therein oil soluble lead soaps of naphregenerated as follows: thenic acids. A middle layer segregates which H Na S contains lead sulfide, sodium hydroxide, sodium gig flfi ggjg gg i soaps, and sodium naphthenates. A lower water t d thbsulfate t s to ayer segreggttes which contains free caustic However, in m 80 111111 1 sodium plum i e and sodium thiosulfates. bu d p in the Silent doctor P the actlon In accordance with the present invention, this oxygen from the a On the Sodlum sulfidesolution is saturated with hydrogen sulfide. The solution is then passed into zone 20 by means of 2Na2s+202+H209Na2s2O3+2NaOH line I 9 wherein the same segregates into an upper When the spent doctor fr m the naphtha treatoil layer which contains naphthenic acids. This mg o e ati i utilized for the treatment of oil layer is withdrawn by means of line 2| and is heating oils, the solution is blown with air in a preferably recycled to line II. The oil layer manner to convert the aromatic mercaptans to however may be withdrawn from the system by means of line 22. By recycling the oil layer to zone I, the naphthenic acids are removed with the spent caustic withdrawn by means of line 13. The lower water layer is withdrawn from zone 20 by means of line 23 and is mixed with caustic free of naphthenic acids introduced by means of line 24. The, solution is? passed intodistillation zone zi wherein temperature and pressure con ditions are adjusted to remove water overhead by means of line 26. A sodium sulfide solution suit?- able for the manufacture oi papercontaining from about 15% is withdrawn from zone 25 by means of line'Z'I.

The present invention isarbroacll y' concerned,-

With the manufacture of asodiu'm sirlfrde' solu tion from a spent doctor solution;- The 'sp'env doctor solution is one which is secured-by first treating a petroleum fraction boiling in the" to 40% oi": sodium suliurlsalts naphtha boiling range and then treating-1a pee troleum fraction boiling in? the heating oil boiling range. process of the; present inventionl mayrbez mores-fully: understood ,by the following example illustrating the same:-

Example A sodium plumbite solution was used to contact ahydrocarbonboiling in the range from about/.1009 F. toA30 E. The spent doctor solutionwas then used. to contact a heating oil beilingzinqthe range from about 550 F. 110700 F: The; spentsolution was allowed to stand wherein; threelayersiormed. of the following amount:v

Vol. per cent Up er layer'; 1 43 6 Intermediate a erZIIIIIII1111111111 23.3: Bower layer l 33.1

Total 1 l 100 ,00:

The segregated mass was treatedwithhydro v gen, sulfide resulting intheformation of two layers. The upper oil layer comprised'511.5.%' oi the total; thelower water.layer.'comprised' 48.5% ofthe. total; The oil layer. contained6.% naphthenic acids and 941% oil, while the water layer, contained 5.9% I sodium .thiosulfate, .'7;9 sodium bisulfide and 86.2% water. ExcessHzS-ismeut'ralized, by. the additionof an alkali metal hysome conditions; a.

;-urating with hydrogen sulfide comprises sodium naphthenates. After contact with hydrogen sulfide; thenaphthemc acids are dissolved in the oil and are recycled, while the sodium sulfur salts concentratein the water layer. Under sediment layer forms after treatmentwithflhydrogen sulfide which is segregated and discarded.

What is'claimed'is:

1. Improved process for the production of a solution comprising sodium sulfur salts which comprises contacting an initial hydrocarbon mixture containing mercaptansand boiling in, themotor ,fuel boiling range with a doctonso. lution,

oil boiling range, withdrawingthe spent-.docton and saturatingthe same with hydrogensulfide. whereby an uppenoil layer containing. naph-r thenic acids and a lower layer containing so.-. dium sulfur salts jorrn, treating vsaidlower layer. with an alkali tal thereafter concentrating the same.

2. Process as defined-by claim 1 whereinsaid initial hydrocarbon boils in the rangefrom aboutv F. andwherein said. secondary.

100 1". to 430 hydrocarbon mixture boils inthe-range from about 430 F. to 750 F.

JOHN B. HOLTZCLAW. JOHN D. BROOKS.

References Cited in the fileof this. patent UNITED STATES PATENTS thereafter using said doctor solutionato; contact a secondary hydrocarbon. mixturecone taining mercaptans, and boiling in the heating,

hydroxide solution. and. 

1. IMPROVED PROCESS FOR THE PRODUCTION OF A 